Research to be undertaken on genetics and physiology of Salmonella typhimurium will deal especially with three topics: 1. Protein and lipopolysaccharide components of the outer membrane in particular: mapping of genes determining outer membrane proteins, and of rfa genes, determining LPS core structure: study of chr mutants, and of other non-virulent mutants expected to be unaltered in antigenic character, in respect of ability to confer immunity when used a "live vaccines". Genes affecting bacteriocin sensitivity. Effect of relevant mutations on survival within mouse phagocytic cells. 2. Effect of defined LPS defects on production of flagella and on motility. 3. Genetics and physiology of plasmids in S. typhimurium, especially enhancement by plasmids of mutagenic effect of visible-light and UV irradiation, and mutator effect of plasmids; mechanism of retardation of growth of E. coli caused by plasmids R46; characterization of group E and related colicins and plasmids.